Module Obj_array

An array of Obj.ts.

This is useful to have as its own type because we can implement faster get and set functions that know that they aren't dealing with float arrays and save a test for it. We also have set avoid the write barrier (caml_modify) in certain situations.

Just like with a regular Array, the elements are boxed so they don't get copied by sub, get, set, blit, etc.

The dynamic check this array module implements is something we hope to have implemented at a lower level (as part of the native compiler's code generation). Given that, the interface is somewhat spartan and intended for use within internal data structures.


type t
val sexp_of_t : t -> Sexplib.Sexp.t
include Blit.S with type t := t
type t
val blit : (t, t) Blit_intf.blit
val blito : (t, t) Blit_intf.blito
val unsafe_blit : (t, t) Blit_intf.blit
val sub : (t, t) Blit_intf.sub
val subo : (t, t) Blit_intf.subo
include Invariant.S with type t := t
type t
val invariant : t Invariant_intf.inv
val create : len:int -> t

create ~len returns an obj-array of length len, all of whose indices have value Obj.repr 0.

val copy : t -> t

copy t returns a new array with the same elements as t.

val singleton : Obj.t -> t
val empty : t
val length : t -> int
val get : t -> int -> Obj.t

get t i and unsafe_get t i return the object at index i. set t i o and unsafe_set t i o set index i to o. In no case is the object copied. The unsafe_* variants omit the bounds check of i.

val unsafe_get : t -> int -> Obj.t
val set : t -> int -> Obj.t -> unit
val unsafe_set : t -> int -> Obj.t -> unit
val unsafe_set_assuming_currently_int : t -> int -> Obj.t -> unit

unsafe_set_assuming_currently_int t i obj sets index i of t to obj, but only works correctly if Obj.is_int (get t i). This precondition saves a dynamic check.

unsafe_set_int_assuming_currently_int is similar, except the value being set is an int.

val unsafe_set_int_assuming_currently_int : t -> int -> int -> unit
val unsafe_clear_if_pointer : t -> int -> unit

unsafe_clear_if_pointer t i prevents t.(i) from pointing to anything to prevent space leaks. It does this by setting t.(i) to Obj.repr 0. As a performance hack, it only does this when not (Obj.is_int t.(i)).

val truncate : t -> len:int -> unit

truncate t ~len shortens t's length to len. It is an error if len <= 0 or len > length t.